1 // SPDX-License-Identifier: GPL-2.0
2 /*
3  * STM32 Low-Power Timer Encoder and Counter driver
4  *
5  * Copyright (C) STMicroelectronics 2017
6  *
7  * Author: Fabrice Gasnier <fabrice.gasnier@st.com>
8  *
9  * Inspired by 104-quad-8 and stm32-timer-trigger drivers.
10  *
11  */
12 
13 #include <linux/bitfield.h>
14 #include <linux/counter.h>
15 #include <linux/mfd/stm32-lptimer.h>
16 #include <linux/mod_devicetable.h>
17 #include <linux/module.h>
18 #include <linux/pinctrl/consumer.h>
19 #include <linux/platform_device.h>
20 #include <linux/types.h>
21 
22 struct stm32_lptim_cnt {
23 	struct device *dev;
24 	struct regmap *regmap;
25 	struct clk *clk;
26 	u32 ceiling;
27 	u32 polarity;
28 	u32 quadrature_mode;
29 	bool enabled;
30 };
31 
stm32_lptim_is_enabled(struct stm32_lptim_cnt * priv)32 static int stm32_lptim_is_enabled(struct stm32_lptim_cnt *priv)
33 {
34 	u32 val;
35 	int ret;
36 
37 	ret = regmap_read(priv->regmap, STM32_LPTIM_CR, &val);
38 	if (ret)
39 		return ret;
40 
41 	return FIELD_GET(STM32_LPTIM_ENABLE, val);
42 }
43 
stm32_lptim_set_enable_state(struct stm32_lptim_cnt * priv,int enable)44 static int stm32_lptim_set_enable_state(struct stm32_lptim_cnt *priv,
45 					int enable)
46 {
47 	int ret;
48 	u32 val;
49 
50 	val = FIELD_PREP(STM32_LPTIM_ENABLE, enable);
51 	ret = regmap_write(priv->regmap, STM32_LPTIM_CR, val);
52 	if (ret)
53 		return ret;
54 
55 	if (!enable) {
56 		clk_disable(priv->clk);
57 		priv->enabled = false;
58 		return 0;
59 	}
60 
61 	/* LP timer must be enabled before writing CMP & ARR */
62 	ret = regmap_write(priv->regmap, STM32_LPTIM_ARR, priv->ceiling);
63 	if (ret)
64 		return ret;
65 
66 	ret = regmap_write(priv->regmap, STM32_LPTIM_CMP, 0);
67 	if (ret)
68 		return ret;
69 
70 	/* ensure CMP & ARR registers are properly written */
71 	ret = regmap_read_poll_timeout(priv->regmap, STM32_LPTIM_ISR, val,
72 				       (val & STM32_LPTIM_CMPOK_ARROK) == STM32_LPTIM_CMPOK_ARROK,
73 				       100, 1000);
74 	if (ret)
75 		return ret;
76 
77 	ret = regmap_write(priv->regmap, STM32_LPTIM_ICR,
78 			   STM32_LPTIM_CMPOKCF_ARROKCF);
79 	if (ret)
80 		return ret;
81 
82 	ret = clk_enable(priv->clk);
83 	if (ret) {
84 		regmap_write(priv->regmap, STM32_LPTIM_CR, 0);
85 		return ret;
86 	}
87 	priv->enabled = true;
88 
89 	/* Start LP timer in continuous mode */
90 	return regmap_update_bits(priv->regmap, STM32_LPTIM_CR,
91 				  STM32_LPTIM_CNTSTRT, STM32_LPTIM_CNTSTRT);
92 }
93 
stm32_lptim_setup(struct stm32_lptim_cnt * priv,int enable)94 static int stm32_lptim_setup(struct stm32_lptim_cnt *priv, int enable)
95 {
96 	u32 mask = STM32_LPTIM_ENC | STM32_LPTIM_COUNTMODE |
97 		   STM32_LPTIM_CKPOL | STM32_LPTIM_PRESC;
98 	u32 val;
99 
100 	/* Setup LP timer encoder/counter and polarity, without prescaler */
101 	if (priv->quadrature_mode)
102 		val = enable ? STM32_LPTIM_ENC : 0;
103 	else
104 		val = enable ? STM32_LPTIM_COUNTMODE : 0;
105 	val |= FIELD_PREP(STM32_LPTIM_CKPOL, enable ? priv->polarity : 0);
106 
107 	return regmap_update_bits(priv->regmap, STM32_LPTIM_CFGR, mask, val);
108 }
109 
110 /*
111  * In non-quadrature mode, device counts up on active edge.
112  * In quadrature mode, encoder counting scenarios are as follows:
113  * +---------+----------+--------------------+--------------------+
114  * | Active  | Level on |      IN1 signal    |     IN2 signal     |
115  * | edge    | opposite +----------+---------+----------+---------+
116  * |         | signal   |  Rising  | Falling |  Rising  | Falling |
117  * +---------+----------+----------+---------+----------+---------+
118  * | Rising  | High ->  |   Down   |    -    |   Up     |    -    |
119  * | edge    | Low  ->  |   Up     |    -    |   Down   |    -    |
120  * +---------+----------+----------+---------+----------+---------+
121  * | Falling | High ->  |    -     |   Up    |    -     |   Down  |
122  * | edge    | Low  ->  |    -     |   Down  |    -     |   Up    |
123  * +---------+----------+----------+---------+----------+---------+
124  * | Both    | High ->  |   Down   |   Up    |   Up     |   Down  |
125  * | edges   | Low  ->  |   Up     |   Down  |   Down   |   Up    |
126  * +---------+----------+----------+---------+----------+---------+
127  */
128 static const enum counter_function stm32_lptim_cnt_functions[] = {
129 	COUNTER_FUNCTION_INCREASE,
130 	COUNTER_FUNCTION_QUADRATURE_X4,
131 };
132 
133 static const enum counter_synapse_action stm32_lptim_cnt_synapse_actions[] = {
134 	COUNTER_SYNAPSE_ACTION_RISING_EDGE,
135 	COUNTER_SYNAPSE_ACTION_FALLING_EDGE,
136 	COUNTER_SYNAPSE_ACTION_BOTH_EDGES,
137 	COUNTER_SYNAPSE_ACTION_NONE,
138 };
139 
stm32_lptim_cnt_read(struct counter_device * counter,struct counter_count * count,u64 * val)140 static int stm32_lptim_cnt_read(struct counter_device *counter,
141 				struct counter_count *count, u64 *val)
142 {
143 	struct stm32_lptim_cnt *const priv = counter_priv(counter);
144 	u32 cnt;
145 	int ret;
146 
147 	ret = regmap_read(priv->regmap, STM32_LPTIM_CNT, &cnt);
148 	if (ret)
149 		return ret;
150 
151 	*val = cnt;
152 
153 	return 0;
154 }
155 
stm32_lptim_cnt_function_read(struct counter_device * counter,struct counter_count * count,enum counter_function * function)156 static int stm32_lptim_cnt_function_read(struct counter_device *counter,
157 					 struct counter_count *count,
158 					 enum counter_function *function)
159 {
160 	struct stm32_lptim_cnt *const priv = counter_priv(counter);
161 
162 	if (!priv->quadrature_mode) {
163 		*function = COUNTER_FUNCTION_INCREASE;
164 		return 0;
165 	}
166 
167 	if (priv->polarity == STM32_LPTIM_CKPOL_BOTH_EDGES) {
168 		*function = COUNTER_FUNCTION_QUADRATURE_X4;
169 		return 0;
170 	}
171 
172 	return -EINVAL;
173 }
174 
stm32_lptim_cnt_function_write(struct counter_device * counter,struct counter_count * count,enum counter_function function)175 static int stm32_lptim_cnt_function_write(struct counter_device *counter,
176 					  struct counter_count *count,
177 					  enum counter_function function)
178 {
179 	struct stm32_lptim_cnt *const priv = counter_priv(counter);
180 
181 	if (stm32_lptim_is_enabled(priv))
182 		return -EBUSY;
183 
184 	switch (function) {
185 	case COUNTER_FUNCTION_INCREASE:
186 		priv->quadrature_mode = 0;
187 		return 0;
188 	case COUNTER_FUNCTION_QUADRATURE_X4:
189 		priv->quadrature_mode = 1;
190 		priv->polarity = STM32_LPTIM_CKPOL_BOTH_EDGES;
191 		return 0;
192 	default:
193 		/* should never reach this path */
194 		return -EINVAL;
195 	}
196 }
197 
stm32_lptim_cnt_enable_read(struct counter_device * counter,struct counter_count * count,u8 * enable)198 static int stm32_lptim_cnt_enable_read(struct counter_device *counter,
199 				       struct counter_count *count,
200 				       u8 *enable)
201 {
202 	struct stm32_lptim_cnt *const priv = counter_priv(counter);
203 	int ret;
204 
205 	ret = stm32_lptim_is_enabled(priv);
206 	if (ret < 0)
207 		return ret;
208 
209 	*enable = ret;
210 
211 	return 0;
212 }
213 
stm32_lptim_cnt_enable_write(struct counter_device * counter,struct counter_count * count,u8 enable)214 static int stm32_lptim_cnt_enable_write(struct counter_device *counter,
215 					struct counter_count *count,
216 					u8 enable)
217 {
218 	struct stm32_lptim_cnt *const priv = counter_priv(counter);
219 	int ret;
220 
221 	/* Check nobody uses the timer, or already disabled/enabled */
222 	ret = stm32_lptim_is_enabled(priv);
223 	if ((ret < 0) || (!ret && !enable))
224 		return ret;
225 	if (enable && ret)
226 		return -EBUSY;
227 
228 	ret = stm32_lptim_setup(priv, enable);
229 	if (ret)
230 		return ret;
231 
232 	ret = stm32_lptim_set_enable_state(priv, enable);
233 	if (ret)
234 		return ret;
235 
236 	return 0;
237 }
238 
stm32_lptim_cnt_ceiling_read(struct counter_device * counter,struct counter_count * count,u64 * ceiling)239 static int stm32_lptim_cnt_ceiling_read(struct counter_device *counter,
240 					struct counter_count *count,
241 					u64 *ceiling)
242 {
243 	struct stm32_lptim_cnt *const priv = counter_priv(counter);
244 
245 	*ceiling = priv->ceiling;
246 
247 	return 0;
248 }
249 
stm32_lptim_cnt_ceiling_write(struct counter_device * counter,struct counter_count * count,u64 ceiling)250 static int stm32_lptim_cnt_ceiling_write(struct counter_device *counter,
251 					 struct counter_count *count,
252 					 u64 ceiling)
253 {
254 	struct stm32_lptim_cnt *const priv = counter_priv(counter);
255 
256 	if (stm32_lptim_is_enabled(priv))
257 		return -EBUSY;
258 
259 	if (ceiling > STM32_LPTIM_MAX_ARR)
260 		return -ERANGE;
261 
262 	priv->ceiling = ceiling;
263 
264 	return 0;
265 }
266 
267 static struct counter_comp stm32_lptim_cnt_ext[] = {
268 	COUNTER_COMP_ENABLE(stm32_lptim_cnt_enable_read,
269 			    stm32_lptim_cnt_enable_write),
270 	COUNTER_COMP_CEILING(stm32_lptim_cnt_ceiling_read,
271 			     stm32_lptim_cnt_ceiling_write),
272 };
273 
stm32_lptim_cnt_action_read(struct counter_device * counter,struct counter_count * count,struct counter_synapse * synapse,enum counter_synapse_action * action)274 static int stm32_lptim_cnt_action_read(struct counter_device *counter,
275 				       struct counter_count *count,
276 				       struct counter_synapse *synapse,
277 				       enum counter_synapse_action *action)
278 {
279 	struct stm32_lptim_cnt *const priv = counter_priv(counter);
280 	enum counter_function function;
281 	int err;
282 
283 	err = stm32_lptim_cnt_function_read(counter, count, &function);
284 	if (err)
285 		return err;
286 
287 	switch (function) {
288 	case COUNTER_FUNCTION_INCREASE:
289 		/* LP Timer acts as up-counter on input 1 */
290 		if (synapse->signal->id != count->synapses[0].signal->id) {
291 			*action = COUNTER_SYNAPSE_ACTION_NONE;
292 			return 0;
293 		}
294 
295 		switch (priv->polarity) {
296 		case STM32_LPTIM_CKPOL_RISING_EDGE:
297 			*action = COUNTER_SYNAPSE_ACTION_RISING_EDGE;
298 			return 0;
299 		case STM32_LPTIM_CKPOL_FALLING_EDGE:
300 			*action = COUNTER_SYNAPSE_ACTION_FALLING_EDGE;
301 			return 0;
302 		case STM32_LPTIM_CKPOL_BOTH_EDGES:
303 			*action = COUNTER_SYNAPSE_ACTION_BOTH_EDGES;
304 			return 0;
305 		default:
306 			/* should never reach this path */
307 			return -EINVAL;
308 		}
309 	case COUNTER_FUNCTION_QUADRATURE_X4:
310 		*action = COUNTER_SYNAPSE_ACTION_BOTH_EDGES;
311 		return 0;
312 	default:
313 		/* should never reach this path */
314 		return -EINVAL;
315 	}
316 }
317 
stm32_lptim_cnt_action_write(struct counter_device * counter,struct counter_count * count,struct counter_synapse * synapse,enum counter_synapse_action action)318 static int stm32_lptim_cnt_action_write(struct counter_device *counter,
319 					struct counter_count *count,
320 					struct counter_synapse *synapse,
321 					enum counter_synapse_action action)
322 {
323 	struct stm32_lptim_cnt *const priv = counter_priv(counter);
324 	enum counter_function function;
325 	int err;
326 
327 	if (stm32_lptim_is_enabled(priv))
328 		return -EBUSY;
329 
330 	err = stm32_lptim_cnt_function_read(counter, count, &function);
331 	if (err)
332 		return err;
333 
334 	/* only set polarity when in counter mode (on input 1) */
335 	if (function != COUNTER_FUNCTION_INCREASE
336 	    || synapse->signal->id != count->synapses[0].signal->id)
337 		return -EINVAL;
338 
339 	switch (action) {
340 	case COUNTER_SYNAPSE_ACTION_RISING_EDGE:
341 		priv->polarity = STM32_LPTIM_CKPOL_RISING_EDGE;
342 		return 0;
343 	case COUNTER_SYNAPSE_ACTION_FALLING_EDGE:
344 		priv->polarity = STM32_LPTIM_CKPOL_FALLING_EDGE;
345 		return 0;
346 	case COUNTER_SYNAPSE_ACTION_BOTH_EDGES:
347 		priv->polarity = STM32_LPTIM_CKPOL_BOTH_EDGES;
348 		return 0;
349 	default:
350 		return -EINVAL;
351 	}
352 }
353 
354 static const struct counter_ops stm32_lptim_cnt_ops = {
355 	.count_read = stm32_lptim_cnt_read,
356 	.function_read = stm32_lptim_cnt_function_read,
357 	.function_write = stm32_lptim_cnt_function_write,
358 	.action_read = stm32_lptim_cnt_action_read,
359 	.action_write = stm32_lptim_cnt_action_write,
360 };
361 
362 static struct counter_signal stm32_lptim_cnt_signals[] = {
363 	{
364 		.id = 0,
365 		.name = "Channel 1 Quadrature A"
366 	},
367 	{
368 		.id = 1,
369 		.name = "Channel 1 Quadrature B"
370 	}
371 };
372 
373 static struct counter_synapse stm32_lptim_cnt_synapses[] = {
374 	{
375 		.actions_list = stm32_lptim_cnt_synapse_actions,
376 		.num_actions = ARRAY_SIZE(stm32_lptim_cnt_synapse_actions),
377 		.signal = &stm32_lptim_cnt_signals[0]
378 	},
379 	{
380 		.actions_list = stm32_lptim_cnt_synapse_actions,
381 		.num_actions = ARRAY_SIZE(stm32_lptim_cnt_synapse_actions),
382 		.signal = &stm32_lptim_cnt_signals[1]
383 	}
384 };
385 
386 /* LP timer with encoder */
387 static struct counter_count stm32_lptim_enc_counts = {
388 	.id = 0,
389 	.name = "LPTimer Count",
390 	.functions_list = stm32_lptim_cnt_functions,
391 	.num_functions = ARRAY_SIZE(stm32_lptim_cnt_functions),
392 	.synapses = stm32_lptim_cnt_synapses,
393 	.num_synapses = ARRAY_SIZE(stm32_lptim_cnt_synapses),
394 	.ext = stm32_lptim_cnt_ext,
395 	.num_ext = ARRAY_SIZE(stm32_lptim_cnt_ext)
396 };
397 
398 /* LP timer without encoder (counter only) */
399 static struct counter_count stm32_lptim_in1_counts = {
400 	.id = 0,
401 	.name = "LPTimer Count",
402 	.functions_list = stm32_lptim_cnt_functions,
403 	.num_functions = 1,
404 	.synapses = stm32_lptim_cnt_synapses,
405 	.num_synapses = 1,
406 	.ext = stm32_lptim_cnt_ext,
407 	.num_ext = ARRAY_SIZE(stm32_lptim_cnt_ext)
408 };
409 
stm32_lptim_cnt_probe(struct platform_device * pdev)410 static int stm32_lptim_cnt_probe(struct platform_device *pdev)
411 {
412 	struct stm32_lptimer *ddata = dev_get_drvdata(pdev->dev.parent);
413 	struct counter_device *counter;
414 	struct stm32_lptim_cnt *priv;
415 	int ret;
416 
417 	if (IS_ERR_OR_NULL(ddata))
418 		return -EINVAL;
419 
420 	counter = devm_counter_alloc(&pdev->dev, sizeof(*priv));
421 	if (!counter)
422 		return -ENOMEM;
423 	priv = counter_priv(counter);
424 
425 	priv->dev = &pdev->dev;
426 	priv->regmap = ddata->regmap;
427 	priv->clk = ddata->clk;
428 	priv->ceiling = STM32_LPTIM_MAX_ARR;
429 
430 	/* Initialize Counter device */
431 	counter->name = dev_name(&pdev->dev);
432 	counter->parent = &pdev->dev;
433 	counter->ops = &stm32_lptim_cnt_ops;
434 	if (ddata->has_encoder) {
435 		counter->counts = &stm32_lptim_enc_counts;
436 		counter->num_signals = ARRAY_SIZE(stm32_lptim_cnt_signals);
437 	} else {
438 		counter->counts = &stm32_lptim_in1_counts;
439 		counter->num_signals = 1;
440 	}
441 	counter->num_counts = 1;
442 	counter->signals = stm32_lptim_cnt_signals;
443 
444 	platform_set_drvdata(pdev, priv);
445 
446 	ret = devm_counter_add(&pdev->dev, counter);
447 	if (ret < 0)
448 		return dev_err_probe(&pdev->dev, ret, "Failed to add counter\n");
449 
450 	return 0;
451 }
452 
453 #ifdef CONFIG_PM_SLEEP
stm32_lptim_cnt_suspend(struct device * dev)454 static int stm32_lptim_cnt_suspend(struct device *dev)
455 {
456 	struct stm32_lptim_cnt *priv = dev_get_drvdata(dev);
457 	int ret;
458 
459 	/* Only take care of enabled counter: don't disturb other MFD child */
460 	if (priv->enabled) {
461 		ret = stm32_lptim_setup(priv, 0);
462 		if (ret)
463 			return ret;
464 
465 		ret = stm32_lptim_set_enable_state(priv, 0);
466 		if (ret)
467 			return ret;
468 
469 		/* Force enable state for later resume */
470 		priv->enabled = true;
471 	}
472 
473 	return pinctrl_pm_select_sleep_state(dev);
474 }
475 
stm32_lptim_cnt_resume(struct device * dev)476 static int stm32_lptim_cnt_resume(struct device *dev)
477 {
478 	struct stm32_lptim_cnt *priv = dev_get_drvdata(dev);
479 	int ret;
480 
481 	ret = pinctrl_pm_select_default_state(dev);
482 	if (ret)
483 		return ret;
484 
485 	if (priv->enabled) {
486 		priv->enabled = false;
487 		ret = stm32_lptim_setup(priv, 1);
488 		if (ret)
489 			return ret;
490 
491 		ret = stm32_lptim_set_enable_state(priv, 1);
492 		if (ret)
493 			return ret;
494 	}
495 
496 	return 0;
497 }
498 #endif
499 
500 static SIMPLE_DEV_PM_OPS(stm32_lptim_cnt_pm_ops, stm32_lptim_cnt_suspend,
501 			 stm32_lptim_cnt_resume);
502 
503 static const struct of_device_id stm32_lptim_cnt_of_match[] = {
504 	{ .compatible = "st,stm32-lptimer-counter", },
505 	{},
506 };
507 MODULE_DEVICE_TABLE(of, stm32_lptim_cnt_of_match);
508 
509 static struct platform_driver stm32_lptim_cnt_driver = {
510 	.probe = stm32_lptim_cnt_probe,
511 	.driver = {
512 		.name = "stm32-lptimer-counter",
513 		.of_match_table = stm32_lptim_cnt_of_match,
514 		.pm = &stm32_lptim_cnt_pm_ops,
515 	},
516 };
517 module_platform_driver(stm32_lptim_cnt_driver);
518 
519 MODULE_AUTHOR("Fabrice Gasnier <fabrice.gasnier@st.com>");
520 MODULE_ALIAS("platform:stm32-lptimer-counter");
521 MODULE_DESCRIPTION("STMicroelectronics STM32 LPTIM counter driver");
522 MODULE_LICENSE("GPL v2");
523 MODULE_IMPORT_NS(COUNTER);
524